1. Field of the Invention
The present invention relates to a fresh-gas or carbureted fuel induction or intake system for turbocharged, in-line, six-cylinder internal combustion engines; the intake or guidance system is arranged between the inlet ports of the cylinders and the supercharging device, and comprises two resonance tanks, each of which individually communicates with the inlet ports of three adjacent cylinders, and the individual volumes of which amount to more than half of, but less than tenfold, the total volume of the three cylinders connected to the respective resonance tank; each resonance tank has associated therewith a resonance pipe, the outlet opening of which opens into the tank, while its inlet opening communicates with the discharge side of the supercharging device; the effective length of each resonance pipe is at least eight times the diameter of a circle having a circular cross-sectional area equivalent to the cross-sectional area of the pipe; the respective resonance tanks with the associated resonance pipes extend in the same direction as the longitudinal axis of the engine.
2. Description of the Prior Art
Fresh-gas intake systems having a combination of exhaust gas turbocharging and resonance supercharging are known (German Pat. No. 22 45 732). They consist of a plenum or compensating tank supplied by the turbocharger, the fresh gas being routed from the plenum tank via two resonance pipes to the resonance tanks which respectively connect the inlet ports of each group of three adjacent cylinders. Such systems have the following drawbacks:
Due to the plenum tanks and resonance pipes being separately arranged from the resonance tanks which are screwed to the cylinder head, there are, in addition to the necessary vibration-resistant and expensive supports, four sealing points which have to seal the resonance system from the outside. These sealing points are expensive because they have to be both gas-tight and oil-tight in view of the general practice of delivering oil-containing engine blowby gases into the fresh gas system.
The externally arranged plenum tanks, and the externally arranged resonance pipes, take up a large amount of space and substantially impair the desirable compactness of the engine envelope which is important in order to make the engine suitable for univeral application.
The externally arranged resonanc pipes increase noise radiation, which is undesirable with a view to satisfying legislation which imposes limitations on noise emission.
The externally arranged resonance pipes generally have to be bent in several planes in order to accommodate them in the crowded space between the resonance and plenum tanks. Bending of the pipes is expensive and problematic, expecially in view of the fact that no creasing is permissible inside the resonance pipes in view of the high flow velocities.
In order to obviate the drawbacks mentioned, systems have been developed where the plenum tanks, resonance pipes, and resonance tanks are combined in one unit; the resonance pipes are generally accommodated in integrated plenum tanks which extend over both resonance tanks in the longitudinal direction of the engine. Such a system was disclosed in German Pat. No. 26 21 638.
Systems of this type are complex, inter alia because of the necessary plenum tank. In the interest of minimizing the physical volume, the integrated resonance pipes have to be made with narrow curvatures which additionally have to blend in with the conically extended throat region, which in most cases can be made only as a casting, so that the resonance pipes--ruling out full-length cast pipes for reasons of excessively rough surfaces, high flow losses, and considerable complexity of the integral casting--have to be "fabricated" from drawn pipes and cast bends at substantial expense. Furthermore, introducing the resonance pipes so fabricated, and securing them in a vibration-resistant manner, inside the unit is complex and expensive.
An object of the present invention is to provide a compact, fresh-gas intake system featuring low flow losses, with the need for an external or integrated plenum tank being eliminated, and with the introduction of the resonance pipes in the integral unit, as well as the supply of the fresh gas, being facilitated.